Methods for producing calcium soaps have been known for many years in the state of the art. Soaps are generally made from natural animal or plant fats containing triglycerides that comprise fatty acids, usually long-chain fatty acids, attached to the glycerol skeleton, which form salts by means of a process of saponification in the presence of bases.
The fatty acids that most commonly form part of these triglycerides are long-chain fatty acids such as oleic, stearic, palmitic, myristic, lauric, linoleic and linolenic acids. Fatty acids with much shorter chains also appear, such as butyric, capric, caprylic and caproic acids.
Strong inorganic alkaline metal bases, such as sodium hydroxide or potassium hydroxide, are chosen as suitable bases for the saponification reaction. In general, alkaline soaps are produced and their use is limited to cosmetics.
In the production of calcium soaps, calcium oxide (CaO) is added to the fats instead of adding alkaline metal hydroxide, which conditions the other parameters of the saponification reaction.
U.S. Pat. No. 4,642,317 discloses a process that makes it possible to increase the proportion of fat fed to ruminants, without having a deleterious effect on the rumen microorganisms, which consists of supplying the animals with fatty acids in the form of previously prepared calcium salts. One of the examples of how to produce the salts from natural fats mentions the prior saponification of the fats with sodium or potassium hydroxide, the separation of the phase containing the alkaline metal salts and the subsequent dissolution of the phase in aqueous medium and mixing it with calcium salts.
U.S. Pat. No. 4,826,694, U.S. Pat. No. 4,853,233 and U.S. Pat. No. 4,909,138 also disclose compositions for feeding ruminants wherein the main component (60-80% of the composition) is calcium or calcium salts of longer-chain fatty acids (mainly with 14 to 18 carbon atoms), although it is also mentioned that the presence of triglycerides (5%-15%) in the end product is important for the composition to be useful as feed for ruminants. The patents also disclose an apparatus and a process for producing the intended compositions, the process comprising, in this case, mixing one or more basic oxides (preferably CaO) in excess with the fatty acids and triglycerides and with water and, optionally, with an additional nutritional material as a source of proteins, thoroughly homogenizing the mixture to bring about the exothermic reaction that forms the corresponding fatty acid salts, then spreading the mixture over a flat surface so that most of the water evaporates. It is mentioned that one of the preferred embodiments of the process involves pre-heating the fatty acids, e.g. to 80 degrees C.-100 degrees C., before mixing them with the source of basic oxide, which is preferably lime (CaO).
Modifications to this basic process have subsequently been disclosed. For example, U.S. Pat. No. 5,234,701 discloses the inclusion of an aqueous solution of sodium carbonate-bicarbonate, which is a residual effluent by-product of a bicarbonate production process, as the aqueous medium for the calcium salt-forming reaction. This addition of sodium carbonate-bicarbonate seems to increase the efficiency of the process, thanks to the formation of a reaction intermediate consisting of the fatty acid sodium salt, which facilitates the formation of the corresponding calcium salt.
Other patents stress the importance of the reaction conditions to produce products with suitable characteristics when using sources of fatty acids wherein a high proportion thereof are present in the form of triglycerides. Thus, for example, U.S. Pat. No. 5,382,678 discloses the importance of mixing the source of fatty acids with the source of alkaline earth metal prior to adding water so that the end product is not a powdery solid, but takes the form of tackless free-flowing granules. It also discloses the importance of maintaining the temperature of the reaction medium at a suitable value (40 degrees C.-130 degrees C.; 110 degrees C. is used in the examples) and for a sufficient time to hydrolyze most of the glycerides that are present, releasing fatty acids that produce the desired alkaline earth metal salts.
U.S. Pat. No. 6,229,031 also highlights the importance of maintaining a suitable temperature for long enough to achieve the saponification of fatty starting materials with more than 45% triglycerides, again mentioning the need to supply the reaction mixture with additional heat as well as that generated by the exothermic reaction itself. In this case, the suitable temperature intervals mentioned are higher (90 degree C.-250 degrees C.), with higher temperatures being preferred the lower the percentage of CaO that is added, which must be between 10% and 30% of the final composition.
U.S. Pat. No. 6,576,667 and U.S. Pat. No. 6,774,252 mention that the final triglyceride content must not exceed 5% of the total composition to prevent undesired alterations during storage, suggesting that the best way to achieve sufficient saponification when using fatty materials rich in triglycerides with a high omega-3 fatty acid content is to use 2 to 3 equivalents of CaO relative to the starting material and 2 to 5 equivalents of water relative to the CaO.
U.S. Published Patent Application No. 20090220638 discloses a process of mixing the natural fats or oils with the calcium oxide, then adding water to the mixture and applying heat in a high pressure reactor. After reacting the fats and/or oils with calcium oxide, the reaction mass is allowed to cool. The calcium soap thus produced contains glycerol from the saponification of the triglycerides. No further washing, concentration (e.g. under vacuum conditions), or similar steps are necessary. The soap need only be formed using conventional techniques of extrusion into blocks, pelletization, compression, granulation, etc. This reference discloses calcium soaps with a high fatty acid content (82-86%) are directly obtained after the saponification process, and is typical of attempts to carry out saponification more effectively, and to handle purification of the saponification reaction mixture (i.e., by using significant excess calcium oxide to drive the reaction to 100% glycerol, etc.).
Other patents relating to calcium soaps in animal feed compositions include U.S. Pat. Nos. 7,318,943; 6,229,031; 5,783,714; 4,221,818; 4,198,294; 4,062,988 and 4,016,296. The foregoing references are hereby incorporated herein by reference.
Accordingly, the prior art has attempted to improve saponification processes applied to fats to maximize the amount of fatty acid salts obtained.
Typical of products currently on the market are 100% calcium soaps, such as Megalac, commercially available from Volac Limited of Royston, England. These products are 100% salts usually of palm oil or soybean oil fatty acids. Such products are generally made by saponification of triglyceride fats, usually palm oil or soybean oil, with technology that is well known. The 100% calcium soaps have a very high melt point (and actually decompose before melting) and thus cannot be prilled effectively.
Beyond the problems of creating magnesium salts of fatty acids of sufficient nutritive value and digestibility (i.e., relatively high salt/free acid ratio, especially for ruminants), another set of concomitant problems are associated with the transportation and use of nutritional supplements of this sort related to their transport, storage, handling and dispensing, and use in processing. One of the problems associated with free fatty acid mixtures (100% non-salted) is that they tend to have relatively low onset melting points such that they may melt when exposed to elevated ambient temperature, such as when stored in silos, packaged in bags, subjected to the heat associated with processing or milling the material with base particulate feeds, or otherwise transporting the material in warmer weather or warm climates.
The relatively low onset melting points also adversely affect handling and dispensing, as it more preferable to handle and dispense materials, both as a consumer and in industrial processing, that flow as a relatively dry, non-tacky particulate.
Another related problem is that the 100% free fatty acid products are subject to caking and agglomeration upon being subjected to pressure, whether as a result of storage in silos, packing and transport in bags, etc.
Likewise, where it is desired to blend or mill such nutritional supplements so as to produce particulate livestock feed blends, current free fatty acid products are subject to melting or liquefaction during processing, making them unsuitable for this type of industrial processing of this type. In this regard, while 100% salt products do have acceptable bulk handling properties and can be pelleted, they cannot be prilled. The 100% calcium salted fatty acid products typically are all made from palm oil or soybean oil and with the higher unsaturated fatty acid level, these products have a negative nutritional effect on the rumen relative to the more saturated free fatty acid mixtures like Energy Booster 100 (EB 100), commercially available from Milk Specialties Global Animal Nutrition of Eden Prairie, Wis.
Accordingly, there remains a need for nutritional supplements comprising fatty acid mixtures or magnesium salts of fatty acids that feature the required nutritive value and digestibility, yet are improved with respect to properties that are important to the transportation, storage, handling and industrial processing applied in the particulate livestock feed blends.